1. Field of the Invention
This invention relates to fuel compositions containing aryl succinimides. More particularly, this invention relates to the use of aryl succinimides in fuel compositions to prevent and control engine deposits.
2. Description of the Related Art
It is well known that automobile engines tend to form deposits on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports and intake valves, due to the oxidation and polymerization of hydrocarbon fuel. These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration. Moreover, engine deposits can significantly increase an automobile's fuel consumption and production of exhaust pollutants. Therefore, the development of effective fuel detergents or "deposit control" additives to prevent or control such deposits is of considerable importance and numerous such materials are known in the art.
For example, aliphatic hydrocarbon-substituted phenols are known to reduce engine deposits when used in fuel compositions. U.S. Pat. No. 3,849,085, issued Nov. 19, 1974 to Kreuz et al., discloses a motor fuel composition comprising a mixture of hydrocarbons in the gasoline boiling range containing about 0.01 to 0.25 volume percent of a high molecular weight aliphatic hydrocarbon-substituted phenol in which the aliphatic hydrocarbon radical has an average molecular weight in the range of about 500 to 3,500. This patent teaches that gasoline compositions containing minor amounts of an aliphatic hydrocarbon-substituted phenol not only prevent or inhibit the formation of intake valve and port deposits in a gasoline engine, but also enhance the performance of the fuel composition in engines designed to operate at higher operating temperatures with a minimum of decomposition and deposit formation in the manifold of the engine.
Similarly, U.S. Pat. No. 4,134,846, issued Jan. 16, 1979 to Machleder et al., discloses a fuel additive composition comprising a mixture of (1) the reaction product of an aliphatic hydrocarbon-substituted phenol, epichlorohydrin and a primary or secondary mono- or polyamine, and (2) a polyalkylene phenol. This patent teaches that such compositions show excellent carburetor, induction system and combustion chamber detergency and, in addition, provide effective rust inhibition when used in hydrocarbon fuels at low concentrations.
Amino phenols are also known to function as detergents/dispersants, antioxidants and anti-corrosion agents when used in fuel compositions. U.S. Pat. No. 4,320,021, issued Mar. 16, 1982 to R. M. Lange, for example, discloses amino phenols having at least one substantially saturated hydrocarbon-based substituent of at least 30 carbon atoms. The amino phenols of this patent are taught to impart useful and desirable properties to oil-based lubricants and normally liquid fuels. Similar amino phenols are disclosed in related U.S. Pat. No. 4,320,020, issued Mar. 16, 1982 to R. M. Lange. Similarly, U.S. Pat. No. 3,149,933, issued Sep. 22, 1964 to K. Ley et al., discloses hydrocarbon-substituted amino phenols as stabilizers for liquid fuels.
U.S. Pat. No. 4,386,939, issued Jun. 7, 1983 to R. M. Lange, discloses nitrogen-containing compositions prepared by reacting an amino phenol with at least one 3- or 4-membered ring heterocyclic compound in which the hetero atom is a single oxygen, sulfur or nitrogen atom, such as ethylene oxide. The nitrogen-containing compositions of this patent are taught to be useful as additives for lubricants and fuels.
Nitro phenols have also been employed as fuel additives. For example, U.S. Pat. No. 4,347,148, issued Aug. 31, 1982 to K. E. Davis, discloses nitro phenols containing at least one aliphatic substituent having at least about 40 carbon atoms. The nitro phenols of this patent are taught to be useful as detergents, dispersants, antioxidants and demulsifiers for lubricating oil and fuel compositions.
Similarly, U.S. Pat. No. 3,434,814, issued Mar. 25, 1969 to M. Dubeck et al., discloses a liquid hydrocarbon fuel composition containing a major quantity of a liquid hydrocarbon of the gasoline boiling range and a minor amount sufficient to reduce exhaust emissions and engine deposits of an aromatic nitro compound having an alkyl, aryl, aralkyl, alkanoyloxy, alkoxy, hydroxy or halogen substituent.
Mannich base condensation products of hydroxyaryl succinimides with aldehydes and amines, and derivatives thereof, are also known in the art as detergent or dispersant additives for lubricating oils and fuels.
For example, U.S. Pat. No. 4,354,950 to Hammond et al. discloses Mannich base derivatives of N-(hydroxyaryl) hydrocarbyl succinimides which are useful as detergent-dispersant additives for lubricating oils. The Mannich base derivatives described in this patent are prepared by reacting a hydrocarbyl substituted succinic anhydride with an aminophenol to produce an intermediate N-(hydroxyaryl) hydrocarbyl succinimide. This intermediate is then reacted with an alkylene diamine or polyalkylene polyamine and an aldehyde in a Mannich base reaction to produce the desired Mannich base derivatives.
U.S. Pat. No. 4,820,432 to Lundberg et al. discloses oil soluble dispersant additives useful in fuel and lubricating oil compositions which are poly (C.sub.5 to C.sub.9 lactone) modified Mannich base adducts made by reacting a C.sub.5 to C.sub.9 lactone, an amine, an aldehyde, an N-hydroxyaryl amine and a hydrocarbyl substituted C.sub.4 to C.sub.10 dicarboxylic acid producing material. The poly (C.sub.5 to C.sub.9 lactone) modified Mannich base adducts described in this patent may be prepared by first reacting an N-hydroxyaryl amine with a hydrocarbyl substituted C.sub.4 to C.sub.10 dicarboxylic acid producing material to form an N-hydroxyaryl hydrocarbyl substituted imide. The N-hydroxyaryl hydrocarbyl substituted imide is then reacted with an amine and an aldehyde in a Mannich base reaction to form an intermediate adduct having an amino functional group capable of initiating lactone ring opening polymerization. This intermediate adduct is subsequently reacted with a C.sub.5 to C.sub.9 lactone to provide the poly (C.sub.5 to C.sub.9 lactone) modified Mannich base adducts.
U.S. Pat. No. 5,266,081 to Avery et al. discloses multifunctional antioxidant, dispersant and detergent additives for fuels and lubricants which are Mannich base products made from an aminosalicylic acid derived hydrocarbon-substituted succinimide. The Mannich base products described in this patent are prepared by first reacting a hydrocarbon-substituted succinic anhydride with an aminosalicylic acid. The intermediate reaction product so produced is then reacted with an aldehyde and an alkylenepolyamine. The Mannich base product of this reaction is subsequently post reacted with a hydrocarbon-substituted succinic anhydride which can be the same as or different from the hydrocarbon-substituted succinic anhydride used to form the intermediate reaction product.
It has now been discovered that certain aryl succinimides in themselves are surprisingly useful for reducing engine deposits, especially intake valve deposits, when employed as fuel additives in fuel compositions.